GB1002450A - Apparatus and method for controlling the deposition of film-forming material on a moving surface - Google Patents

Abstract

1,002,450. Web coating apparatus. CROWN ZELLERBACH CORPORATION. Dec. 31,1962, No. 49138/62. Heading D1L. [Also in Division B5] Apparatus for casting a coating on to a moving sheet to be coated is adapted to maintain a gaseous pressure on the trailing face of the coating different from that on the leading face, the pressure being applied to the trailing face by conveying the gas through a plurality of adjacent independent passageways of a chamber opening toward the trailing face at a slit of a nozzle adjacent to the moving sheet and immediately behind the coating nozzle. Generally atomospheric pressure is allowed to act on the leading face and a negative gaseous pressure is maintained on the trailing face, e.g. by the action of a suction fan. Apparatus as shown, adapted for casting a film 8 (Fig. 1) on a moving surface 3 is adapted to maintain a gaseous pressure on the trailing face of the film 11 (Fig. 2) different from that on the leading face 12, pressure being applied to the trailing face by conveying the gas through a plurality of adjacent independent passageways 24 (Fig. 3) of a chamber 9 opening toward the trailing face at slit 22 of nozzle 21 adjacent to the moving surface 3, and immediately behind the casting nozzle 4. Generally atmospheric pressure is allowed to act on the leading face and a negative gaseous pressure is maintained on the trailing face (e.g. by suction fan 19). Pressure in the respective passagewyas is selectively regulated by slide valve 28, 29 (Fig. 4) the total pressure being regulated by slide valve 32, 33 (Fig. 3). Thus the applied pressure may be equalized along the whole width of the slit 22. A barrier 23 extends the whole width of the slit between chamber 9 and moving surface 3, to prevent ingress of air. Regulation of the applied pressure as described enables very uniform thickness film to be obtained. Specification 741,818 is referred to.